Furnace Blower Fan on 100% of the time - Good or Bad or it depends?

I was at a dinner party last night and two guests described how their HVAC reps told them to run their furnace blowers 100% of the time. The HVAC reps reasons for the recommendation, as relayed by the dinner guests, were:

1. continuous running reduces the wear and tear on the blower motor that cycling on and off causes, thereby avoiding an earlier motor replacement

2. circulating the air around the home provides better balanced temperatures throughout the home and,

3. continuous air flow would provide cleaner air due to the continuous filtering.

We live in northern Michigan and are a heating dominate climate. I am curious to hear from the HVAC professionals about what they recommend to their clients and why. At the moment I don't buy the above arguments and feel those customers end up paying more in energy costs for little benefit. However I do understand there is no disputing tastes when talking about perceived comfort. Also if anyone knows of a good source or any research done on this issue I would like to see a more in depth analysis (if its out there).

[NOTE: Neither home has an ERV, HRV, or other mechanical ventilation other than intermittent bath and kitchen fans. Both are natural gas, forced air furnaces.]

Replies to This Discussion

Your furnace had a variable speed (DC) motor on the inducer assembly as well as the main blower. Both are ECM motors.

The gas smell is something you should not put off. You can use soap bubbles to check pipe connections but be sure to was the soap off (there is a chemical in soap that helps clean dishes but will corrode pipe or thin wall tubing like flex connectors) There is leak/bubble solutions available at hardware store that are designed for that purpose. A very small leak will have a noticable smell. especially in a confined area.

Your comments on the design are interesting. Most furnaces like this are installed in closets with little to no acces on the side. The access to the motor is through the front. You need to remove the control board and the baffle or block off plate is the panel behind the control board. The flues can be cut above where they exit the furnace nd the sections removed. when you reinstall them use a rubber sleeve (hardware store has them for plumbing pipe) and use the clamps provided to secure them in place. I dont think you problem is in the main blower.

Try running the blower with the heat turned off. See if you have the smell? If you dont, try seeing if the smell starts when the inducer motor starts when the furnace calls for heat with the fan switch at the thermostat set to auto.

I ran into a furnace one time that was working perfectly but had an odor when heating - took the blower out and found a vitamin on top of the heat exchanger that was outgassing (stinking LOL) when heated. you may be experiancing sometjing like that. Do you have the odor when the A/C is on?

Your furnace had a variable speed (DC) motor on the inducer assembly as well as the main blower. Both are ECM motors.

Thanks Steve, Not sure how excited I am in doing all of this cutting and removing all this on my own, since I have very little experience with furnaces.
The gas smell is something you should not put off. You can use soap bubbles to check pipe connections but be sure to was the soap off (there is a chemical in soap that helps clean dishes but will corrode pipe or thin wall tubing like flex connectors) There is leak/bubble solutions available at hardware store that are designed for that purpose. A very small leak will have a noticable smell. especially in a confined area.

Your comments on the design are interesting. Most furnaces like this are installed in closets with little to no acces on the side. The access to the motor is through the front. You need to remove the control board and the baffle or block off plate is the panel behind the control board. The flues can be cut above where they exit the furnace nd the sections removed. when you reinstall them use a rubber sleeve (hardware store has them for plumbing pipe) and use the clamps provided to secure them in place. I dont think you problem is in the main blower.

Try running the blower with the heat turned off. See if you have the smell? If you dont, try seeing if the smell starts when the inducer motor starts when the furnace calls for heat with the fan switch at the thermostat set to auto.

I ran into a furnace one time that was working perfectly but had an odor when heating - took the blower out and found a vitamin on top of the heat exchanger that was outgassing (stinking LOL) when heated. you may be experiancing sometjing like that. Do you have the odor when the A/C is on?

Thanks Steve, not sure how comfortable I feel about cutting into the duct work and removing all the guts since I have very little experience with furnaces. You say "Your furnace had a variable speed (DC) motor on the inducer assembly as well as the main blower. Both are ECM motors." Is this all in behind the block? I do not see anything that looks like a baffle. Do I have a baffle and if so, just where is it located? This smell is becoming intermittent, at times I can smell it when the furnace goes on, other times I cannot smell it. But when you do smell it, it stays with you for a while, causes headaches and then it disappears. Then the furnace will go on and you won't smell anything. I know I am not going crazy since 3 of us had smelled it when the furnace kicks on....but then goes away when it shuts down, and you don't know when it will cause this odor again....it's hit or miss. But I am convinced this smell has something to do with the furnace.
Thanks again for your help...much appreciated

Your furnace had a variable speed (DC) motor on the inducer assembly as well as the main blower. Both are ECM motors.

Steve,
Just what is inside or behind the board? When looking down, I can see a cover which I assume is the blower, but is this blower also a motor or are there 2 motors in there?
In my closet area I have so much room on the left side that an access panel would have been a breeze. Maybe there is a way to cut one...a dumb thought, but I have had dumber ones.
The gas smell is something you should not put off. You can use soap bubbles to check pipe connections but be sure to was the soap off (there is a chemical in soap that helps clean dishes but will corrode pipe or thin wall tubing like flex connectors) There is leak/bubble solutions available at hardware store that are designed for that purpose. A very small leak will have a noticable smell. especially in a confined area.

Your comments on the design are interesting. Most furnaces like this are installed in closets with little to no acces on the side. The access to the motor is through the front. You need to remove the control board and the baffle or block off plate is the panel behind the control board. The flues can be cut above where they exit the furnace nd the sections removed. when you reinstall them use a rubber sleeve (hardware store has them for plumbing pipe) and use the clamps provided to secure them in place. I dont think you problem is in the main blower.

Try running the blower with the heat turned off. See if you have the smell? If you dont, try seeing if the smell starts when the inducer motor starts when the furnace calls for heat with the fan switch at the thermostat set to auto.

I ran into a furnace one time that was working perfectly but had an odor when heating - took the blower out and found a vitamin on top of the heat exchanger that was outgassing (stinking LOL) when heated. you may be experiancing sometjing like that. Do you have the odor when the A/C is on?

That is usually something a knowledgable service tech will do. It is involved for a home owner to accomplish.

The inducer motor ( the small black vent assembly in the front lower door has a small variable spped (ECM) motor on it to adjust flow as the furnace stages from low to high fire.

The main blower motor is also a variable speed motor (ECM) located behing the bulkhead/baffle in the top compartment.

You might want to look at how your duct is sealed in the room. If the water heater ( gas) is in the same room any negative pressure could over come the natural draft of the water heater and caus intermitant oders as flue gasses are pulled into the room.

Can you go to my member page and send me an email with the model and serial #'s. I will get a manual for you and send it to you . Send me some pics of the furnace, fues and water heater if it is in the same room, if you can.

There is really no way to truly diagnose this with out actually inspecting and testing it. I will diagnose for free if you pay the milage. $1.50/ one way LOL the email might be cheaper and then you can print it off and let the next service person look it over with something to refer to.

Have you taken the front doors off the furnace or are you looking down through or around the flue pipes?

I am attaching a picture of an upflow furnace, the components are approx the same - Just turn the pic upside down LOL Really the fan located in the bottom compartment in the pic is located at the top compartment in your furnace. There is a solid baffle/panel on your furnace located behind the control board to isolate the main blower from the flues and burner compartment. the inducer motor is located/ attached to the plactic flue pipe on the right side of the furnace( This is the exhaust) The center plastic pipe attached to a ring on the top of the burner box

Cutting a hole in the side of the furnace wont get you anywhere The blower motor is located on the right side and the blower assembly is mounted in a slide that holds the assembly in place and allows the assembly to slide out the front.

Model and serial #'s will be located in the burner compartment (lower door) on a tag to the right ( usually)

Im going out this evening and wont reply till Monday if you have any questions

Have you taken the front doors off the furnace or are you looking down through or around the flue pipes?

I will send you pictures of the room and get the model number etc. Instead of the $1.50 charge, how about a Chicago Pizza which you will never forget, the drive you will.
I am attaching a picture of an upflow furnace, the components are approx the same - Just turn the pic upside down LOL Really the fan located in the bottom compartment in the pic is located at the top compartment in your furnace. There is a solid baffle/panel on your furnace located behind the control board to isolate the main blower from the flues and burner compartment. the inducer motor is located/ attached to the plactic flue pipe on the right side of the furnace( This is the exhaust) The center plastic pipe attached to a ring on the top of the burner box

Cutting a hole in the side of the furnace wont get you anywhere The blower motor is located on the right side and the blower assembly is mounted in a slide that holds the assembly in place and allows the assembly to slide out the front.

Model and serial #'s will be located in the burner compartment (lower door) on a tag to the right ( usually)

Im going out this evening and wont reply till Monday if you have any questions

Have you taken the front doors off the furnace or are you looking down through or around the flue pipes?

Steven, I just had my next door neighbor over who used to work in the HVAC business years ago and agrees with me about the poor design of this thing, but the good thing is he also could smell it and said it smells like the same type of oily smell they smell at their shop...he repairs giant motors. He asked why we just couldn't remove the Plenum or one side of it and get to the motor which would be basically right at the same level if you took off a side or two, like the front and left side. What do you think? I am not sure how to upload any pictures on here, but will learn.
And I forgot my question when you replied "That is something a knowledgable service tech will do"?
I think I am either becoming brain dead from all of this or the fumes. My girlfriend yesterday said " why don't you get a paraket
I am attaching a picture of an upflow furnace, the components are approx the same - Just turn the pic upside down LOL Really the fan located in the bottom compartment in the pic is located at the top compartment in your furnace. There is a solid baffle/panel on your furnace located behind the control board to isolate the main blower from the flues and burner compartment. the inducer motor is located/ attached to the plactic flue pipe on the right side of the furnace( This is the exhaust) The center plastic pipe attached to a ring on the top of the burner box

Cutting a hole in the side of the furnace wont get you anywhere The blower motor is located on the right side and the blower assembly is mounted in a slide that holds the assembly in place and allows the assembly to slide out the front.

Model and serial #'s will be located in the burner compartment (lower door) on a tag to the right ( usually)

Im going out this evening and wont reply till Monday if you have any questions

Steven,
My neighbor came over tonight and he could smell this oily smell also. He said it smells like the oil they use at their shop...he repairs giant motors. He said why couldn't we just take off a side or two of the Plenum and get to the motor from their...sounded good to me. Your thoughts.
I forgot my question when you answered "That is usually something a knowledgable service tech will do".
I think I am becoming brain dead from all of this. Not sure how to upload pictures to here but will learn.

When you are writing a responce. there is a camera symbal at the top of the reply box. Locate the images you want on your computer and select them. The program will upload them into the message.

The model number is TDX060R936W. I do have the installers guide manual. On this they have circled DY060R9V3W.
I will get pictures going soon. He did not open the return and look down, I did that and just saw the cover on top of the motor. That's when my neighbor thought of taking the Plenum off to see if we could get to the motor.
Variable speed motors do not have oiler ports. The motor is made so that parts are replaced (bearings, armature, module and such) rather than the entire motor.

Get me the MODEL #'s so I can get you the manual. Other wise there is little I can do past what we have already discussed.